The present invention relates to a method for magnifying torque at driveaway of a motor vehicle with the aid of a clutch.
During driveaway of a motor vehicle, if the accelerator pedal delivery is too low, and/or engaging or releasing the clutch is performed too rapidly, the engine torque in the lower speed range can fall off so sharply that the engine of the vehicle, developed as an internal combustion engine, can be shut off without intending to do so. Especially in the case of beginner drivers or during driveaway on an uphill street, this danger increases still more.
It is true that fast-reacting idle controllers for keeping up a minimum idling speed of the internal combustion engine are conventional, but even with those, undesired shutoff of the internal combustion engine cannot certainly be prevented, since at fast release of the clutch, the load increase is so strong that, in this very low speed range, the low engine torque falls off correspondingly strongly. Therefore, to solve this problem, as is conventional, one has to press harder on the accelerator pedal, which leads to increased (fuel) use and noise pollution, or the clutch has to be operated more sensitively, which is a matter of skill of the driver in question.
It is an object of the present invention to provide a method by which the driveaway of a motor vehicle from a standing position is made easier, and by which unwanted shutoff (stalling) of the internal combustion engine is prevented.
The above and other beneficial objects of the present invention are achieved by providing a method as described herein.
According to the present invention, the driver-selected torque is dynamically raised in time, the resulting torque increase preventing the internal combustion engine from coming to an unwanted stop, even if the driver operates the accelerator pedal too little or the clutch moves in too fast. With increasing vehicle speed, the enhancement component is then quickly reduced, so as, for example, not to trigger any accelerator pedal reactions that are too vehement, when parking or leaving a parking space. All in all, the driveaway behavior of the vehicle is perceptibly improved and facilitated.
Reduction of the enhancement component to a value of 0 is already reached at travel speeds of 5 to 10 km/h, because already then no further driveaway problems may appear any more, and this reduction then facilitates getting in and out of a parking space.
Reducing the enhancement component is even reinforced or speeded up by the fact that it is additionally reduced also by the approach of the actual value of the torque to the driver-selected torque correspondingly down to an enhancement component 0. Hereby, on the one hand, a comfortable and safe driveaway is ensured, but then there is a very rapid reduction of the enhancement component, which has a favorable impact especially when entering and leaving a parking space. In this connection, the increased reduction of the enhancement component occurs as a function of the difference between the actual value of the torque and the driver-selected torque.
The enhancement component may be formed with the aid of a speed-dependent multiplication factor, this being lowered by a functional step from the initial value 1, with increasing speed, down to a value of 0, which is reached at a specifiable speed. This multiplier is then linked or multiplied with a definable value to form a multiplication factor. Thus, by this functional step, the speed-dependent reduction of the enhancement component may be functionally set.
In one example embodiment of the method according to the present invention, the difference value between actual value of the torque and driver-selected torque have the multiplication factor applied to them, and the value thus obtained is added to the driver-selected torque for achieving a magnified torque value. It is achieved thereby that the enhancement component is reduced, proportionally to the difference value, even independently of the effect of the functional step, in order thus to contribute to a gentle feedback to the driver-selected torque or the driver setpoint torque.
The enhancement may be limited, even independently of the effect of the functional step, to that time interval during which the actual engine torque is less than the driver-selected torque.
For performing the method, a microcomputer may be provided, which may be, for example, the microcomputer in the central vehicle electronics or the engine electronics, which is present anyway.
An example embodiment of the present invention is illustrated in the drawing and explained in detail below.